A Three-stage Pulse Excitation and Feature Extraction Ultrasonic Ranging Method

Abstract

The invention relates to a three-stage impulse excitation and feature extraction-based ultrasonic distance measurement method. According to the method, three-stage pulse alternating excitation is carried out on an ultrasonic transmitter, and at the same time, a 12-bit A / D synchronous and high-speed acquisition is performed on ultrasonic received signals in a certain period; envelope extraction is performed on the ultrasonic received signals, the envelope line of the signals is extracted through sine fitting; on the basis that the envelope line is smoothed, a maximum envelope peak, that is, the location of a middle envelope peak, is found through global search; with the maximum envelope peak adopted as a starting point, in a local interval, a transition valley point is found through a minimum value forward search method; and a measurement distance is calculated through the calibration relationship of the position of the transitional valley point and the measurement distance. With the three-stage impulse excitation and feature extraction-based ultrasonic distance measurement method of the invention adopted, the problem of slow oscillation decay under unidirectional pulse excitation can be solved; and a three-stage pulse alternating excitation mode is adopted, namely, a forward excitation-reverse excitation-forward excitation mode is adopted, and therefore, an ultrasonic receiver can be in a non-oscillation state before next measurement is performed.

Description

technical field [0001] The invention belongs to the technical field of ultrasonic distance measurement, in particular to an ultrasonic distance measurement method with three-stage pulse excitation and feature extraction. Background technique [0002] As an active non-contact measurement technology, ultrasonic ranging has a series of characteristics such as concentrated direction, strong penetrating power, and slow energy attenuation. It is widely used in the field of modern industrial measurement and control, such as distance measurement, liquid level measurement, ultrasonic flaw detection , automatic parking system and reversing radar system. At the present stage, the domestic and foreign methods of ultrasonic ranging are mainly divided into multi-frequency ranging method, phase difference detection method, time-of-flight detection method and so on. Among these three measurement methods, the time-of-flight detection method is the most widely used because of its simple oper...

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Problems solved by technology

[0003] In the traditional time-of-flight detection method, the ultrasonic transmitter sends a certain number of pulse excitation waves each time. Due to the superposition of energy, the ultrasonic wave received by the ultrasonic transducer is a sinusoidal modulation signal with a slow undulating envelope. Time-of-flight distance measurement is realized at the start-up time point or envelope peak point of the wave. The main technical difficulty of the time-of-flight method is that the start-up time of the ultrasonic sensor has a rise time, which makes the received wave have an inertial delay, and the amplitude of the ultrasonic signal changes. Small, the start-up characteristics are not obvious, and there is a large error in the detection of the start-up time point

However, the ultrasonic envelope curve obtained by the traditional ultrasonic excitation method only appears the peak of the envelope wave once. When the peak of the ultrasonic received signal changes smoothly or tends to be saturated, the peak point of the envelope curve is not unique, and there will be relatively large Large errors affect the final measurement accuracy

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